A photonic integrated circuit (photonic IC (PIC)) is a device that integrates photonic functions for information signals imposed on electromagnetic waves, e.g., electromagnetic waves of optical wavelengths. PICs find application in fiber-optic communication, medical, security, sensing, and photonic computing systems.
Coupling a fiber-optic cable, also sometimes referred to as “optical fiber” or, simply, a “fiber,” to a PIC so that electromagnetic signals, e.g., optical signals, may exchange between the two is challenging because of the large difference between the mode-field diameter of a fiber and that of a PIC. One way to couple a PIC to a fiber is to implement edge-coupling by using an intermediate optical coupling structure (OCS) (sometimes referred to as “fiber assembly unit” (FAU)) that has one end coupled to a fiber and an opposite end placed proximate to a PIC die (i.e., a die that houses one or more PICs) so that electromagnetic signals may be exchanged between the PICs of the PIC die and the fiber, via the OCS.